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The long-term risks of the keto weight-loss diet

The keto weight-loss diet that is having a surge of popularity may actually be shortening people’s lives.

QUESTION: People I know have lost a lot of weight on the keto diet and claim to feel amazing. I worry about the long-term health effects of such a drastic diet, so haven’t tried it. What’s your opinion? I take your point that we’d be better off if we didn’t think thinner was better.

ANSWER: You’re right to worry. The keto – or ketogenic – diet has been dominating water-cooler talk in workplaces this year, yet studies of such low-carbohydrate diets sound alarm bells. Attendees at the European Society of Cardiology Congress in August, for instance, heard that very low-carb diets may, in fact, be killing us.

Despite the recent hype, people have been eating ketogenic diets for nearly 100 years, although not to lose weight. Rather, they’ve been successfully using it to treat drug-resistant epilepsy, especially in children.

The basis of the keto diet for weight loss is that when our body doesn’t get enough carbohydrates, it starts burning fat for fuel. This process is called ketosis and production of ketones is the end result. A keto diet deliberately induces ketosis.

We can probably thank American Dr Robert Atkins for introducing the very-low-carbohydrate diet to the masses of people trying to lose weight. The Atkins diet fad of the early 2000s involved a strict introductory two-week ketogenic phase before switching to a low-carbohydrate regime.

In keto diet-land, some followers restrict their carbohydrate intake to 15-30g a day, but others allow themselves up to 50g. To put that in perspective, a medium-sized banana has 23g of carbs, so that would be your daily allowance on a strict keto diet. The rest of the diet consists mostly of meat, fish, eggs, cheese, butter, oil, cream, green leafy vegetables and nuts. Grain products including breads, pasta, flour and rice, legumes such as beans, potatoes and other starchy vegetables, and many fruits are completely off the menu.

There’s no question the keto diet can result in short-term weight loss. But few people manage to stick to it because of the limited food available and side effects such as constipation, headaches, bad breath and more.

Research suggests 60% of keto dieters have persistent, long-term constipation. Aside from discomfort and fatigue, constipation increases the risk of painful haemorrhoids and reduces disease immunity. It’s also worrying in the context of New Zealand’s woeful colorectal cancer statistics.

Given the strong evidence that eating whole grains and dietary fibre decreases the risk of colorectal cancer, and that red- and processed-meat consumption has the opposite effect, the keto diet gets a fail on both scores.

What’s more, the research presented three months ago to the Munich meeting of cardiologists, which followed nearly 25,000 Americans for a decade, found people who follow a low-carb diet have a greater risk of premature death.

Study participants with the lowest carbohydrate intake, compared with those whose diets were highest in carbs, had a 32% greater risk of all-cause death over an average 6.4-year follow-up. Their risks of death from coronary heart disease, cerebrovascular disease and cancer were increased by 51%, 50% and 35%, respectively.

Other research, involving nearly 450,000 people over 15.6 years, found 15%, 13% and 8% increased risks in total, cardiovascular and cancer mortality, respectively, with low- versus high-carbohydrate diets.

Interestingly, they found the link between low-carb diets and increased risk of all-cause death was greater for non-obese adults, and those aged 55 years and over.

The author of the latter study, Maciej Banach, of the Medical University of Łódź, Poland, said: “Our research highlights an unfavourable association between low-carbohydrate diets and total and cause-specific death, based on individual data and pooled results of previous studies. The findings suggest that low-carbohydrate diets are unsafe and should not be recommended.”

This article was first published in the December 15, 2018 issue of the New Zealand Listener.